Arc fault detection arrangement for a DC electric bus

Abstract

An arc fault detection arrangement for a DC electric bus, the DC electric bus having one or more electric lines adapted to electrically connect a source section and a load section of an electric apparatus, the arc fault detection arrangement including an arc fault detector adapted to receive and process detection signals indicative of AC currents flowing along the electric lines. The arc fault detection arrangement comprises a current sensing device including: primary winding means including a first primary winding conductors and a second primary winding conductors adapted to be electrically connected in series with source portions and load portions of corresponding first and second line conductors of the electric lines, so that common-mode electric currents flowing along the first and second primary winding conductors generate magnetic fluxes with opposite directions; secondary winding means magnetically coupleable with the first primary winding means, the secondary winding means comprising a first secondary winding conductor electrically connected with the arc fault detector to provide the detection signals to the arc fault detector.

The invention claimed is: 
     
       1. An arc fault detection arrangement for a DC electric bus, said DC electric bus having one or more electric lines (L 1 , L 2 , LN) adapted to electrically connect a source section and a load section of an electric apparatus, said arc fault detection arrangement comprising an arc fault detector adapted to receive and process detection signals (DS) indicative of AC currents flowing along said electric lines (L 1 , L 2 , LN) characterised in that it comprises a current sensing device comprising:
 a common magnetic core forming a magnetic circuit; 
 primary and secondary winding means magnetically associated to said magnetic circuit; 
 
       wherein said primary winding means comprises one or more first primary winding conductors (PW 1   1 , PW 1   2 , PW 1   N ) and one or more second primary winding conductors (PW 2   1 , PW 2   2 , PW 2   N ) adapted to be electrically connected in series with source portions (C 1   S , C 2   S ) and load portions (C 1   L , C 2   L ) of corresponding first and second line conductors (C 1 , C 2 ) of said electric lines (L 1 , L 2 , LN), so that common-mode electric currents flowing along said first and second primary winding conductors (PW 1   1 , PW 1   2 , PW 1   N , PW 2   1 , PW 2   2 , PW 2   N ) generate magnetic fluxes with opposite directions; 
       wherein said secondary winding means are magnetically coupleable with said first primary winding means, said secondary winding means comprising at least a first secondary winding conductor (SW 1 ) electrically connected with said arc fault detector to provide said detection signals (DS) to said arc fault detector. 
     
     
       2. The arc fault detection arrangement, according to  claim 1 , wherein said first and second primary winding conductors (PW 1   1 , PW 1   N , PW 2   1 , PW 2   N ) are adapted to be electrically connected to the source portions (C 1   S , C 2   S ) and the load portions (C 1   L , C 2   L ) of corresponding first and second line conductors (C 1 , C 2 ) with mutually opposite polarities. 
     
     
       3. The arc fault detection arrangement, according to  claim 2 , wherein
 said first primary winding conductors (PW 1   1 , PW 1   N ) have positive terminals (T 1 ) adapted to be electrically connected with corresponding source terminals (ST 1 ) of the source portions (C 1   S ) of said first conductors (C 1 ) and negative terminals (T 2 ) adapted to be electrically connected with corresponding load terminals (LT 1 ) of the load portions (C 1   L ) of said first conductors C 1 ; 
 said second primary winding conductors (PW 2   1 , PW 2   N ) have positive terminals (T 3 ) adapted to be electrically connected with corresponding load terminals (LT 2 ) of the load portions C 2   L  of said second conductors (C 2 ) and negative terminals (T 4 ) adapted to be electrically connected with corresponding source terminals (ST 2 ) of the source portions (C 2   S ) of said second conductors C 2 . 
 
     
     
       4. The arc fault detection arrangement, according to  claim 2 , wherein said secondary winding means comprise at least a second secondary winding conductor (SW 2 ) electrically connected with said arc fault detector to receive a test current provided by said arc fault detector. 
     
     
       5. The arc fault detection arrangement, according to  claim 2 , wherein:
 said first primary winding conductors (PW 1   1 , PW 1   N ) have positive terminals (T 1 ) adapted to be electrically connected with corresponding load terminals (LT 1 ) of the load portions (C 1   L ) of said first conductors (C 1 ) and negative terminals (T 2 ) adapted to be electrically connected with corresponding source terminals (ST 1 ) of the source portions (C 1   S ) of said first conductors (C 1 ); 
 said second primary winding conductors (PW 2   1 , PW 2   N ) have positive terminals (T 3 ) adapted to be electrically connected with corresponding source terminals (ST 2 ) of the source portions (C 2   S ) of the second conductors (C 2 ) and negative terminals (T 4 ) adapted to be electrically connected with corresponding load terminals (LT 2 ) of the load portions (C 2   L ) of said second conductors C 2 . 
 
     
     
       6. The arc fault detection arrangement, according to  claim 2 , wherein said secondary winding means comprise at least a second secondary winding conductor (SW 2 ) electrically connected with said arc fault detector to receive a test current provided by said arc fault detector. 
     
     
       7. The arc fault detection arrangement, according to  claim 2 , wherein said first primary winding conductors (PW 1   1 , PW 1   2 , PW 1   N ) and/or said second primary winding conductors (PW 2   1 , PW 2   2 , PW 2   N ) are formed by corresponding rigid conductive elements. 
     
     
       8. The arc fault detection arrangement, according to  claim 2 , wherein said first primary winding conductors (PW 1   1 , PW 1   2 , PW 1   N ) and/or said second primary winding conductors (PW 2   1 , PW 2   2 , PW 2   N ) are formed by corresponding conductive tracks. 
     
     
       9. The arc fault detection arrangement, according to  claim 2 , wherein said magnetic circuit has a relative magnetic permeability lower than or equal to 150. 
     
     
       10. The arc fault detection arrangement, according to  claim 1 , wherein said secondary winding means comprise at least a second secondary winding conductor (SW 2 ) electrically connected with said arc fault detector to receive a test current provided by said arc fault detector. 
     
     
       11. The arc fault detection arrangement, according to  claim 1 , wherein said first primary winding conductors (PW 1   1 , PW 1   2 , PW 1   N ) and/or said second primary winding conductors (PW 2   1 , PW 2   2 , PW 2   N ) are formed by corresponding rigid conductive elements. 
     
     
       12. The arc fault detection arrangement, according to  claim 11 , wherein said current sensing device comprises:
 an outer enclosure fixable to a support and adapted to define a volume, in which said core and said secondary winding means are accommodated; 
 one or more first conductive bridges (PW 1   1 , PW 1   2 ) forming said first primary winding conductors, said first conductive bridges being coupleable with said support and arranged externally to said outer enclosure; 
 one or more second conductive bridges (PW 2   1 , PW 2   2 ) forming said second primary winding conductors, said second conductive bridges being coupleable with said support and arranged externally to said outer enclosure. 
 
     
     
       13. The arc fault detection arrangement, according to  claim 12 , wherein said outer enclosure comprises first retaining means adapted to be removably coupled with said first conductive bridges (PW 1   1 , PW 1   2 ). 
     
     
       14. The arc fault detection arrangement, according to  claim 13 , wherein said outer enclosure comprises second retaining means adapted to be removably coupled with said second conductive bridges (PW 2   1 , PW 2   2 ). 
     
     
       15. The arc fault detection arrangement, according to  claim 12 , wherein said outer enclosure comprises second retaining means adapted to be removably coupled with said second conductive bridges (PW 2   1 , PW 2   2 ). 
     
     
       16. The arc fault detection arrangement, according to  claim 1 , wherein said first primary winding conductors (PW 1   1 , PW 1   2 , PW 1   N ) and/or said second primary winding conductors (PW 2   1 , PW 2   2 , PW 2   N ) are formed by corresponding conductive tracks. 
     
     
       17. The arc fault detection arrangement, according to  claim 16 , wherein said current sensing device comprises:
 one or more first primary conductive tracks (PW 1   1 ) forming said first primary winding conductors, said first primary conductive tracks being deposited on said support; 
 one or more second primary conductive tracks (PW 2   1 ) forming said second primary winding conductors, said second primary conductive tracks being deposited on said support. 
 
     
     
       18. The arc fault detection arrangement, according to  claim 1 , wherein said magnetic circuit has a relative magnetic permeability lower than or equal to 150. 
     
     
       19. A photovoltaic electric power generation apparatus comprising:
 a source section comprising at least a photovoltaic panel adapted to provide DC electric power; 
 a load section comprising at least an inverter section adapted to receive DC electric power and provide AC electric power; 
 a DC electric bus having one or more electric lines (L 1 , LN) electrically connecting said source section with said load section; 
 an arc fault detection arrangement, according to  claim 1 , operatively associated with said DC electric bus. 
 
     
     
       20. A current sensing device for an arc fault detection arrangement for a DC electric bus, said DC electric bus having one or more electric lines (L 1 , L 2 , LN) adapted to electrically connect a source section and a load section of an electric apparatus, wherein the current sensing device comprises:
 a common magnetic core forming a magnetic circuit; 
 primary and secondary winding means magnetically associated to said magnetic circuit; 
 
       wherein said primary winding means comprises one or more first primary winding conductors (PW 1   1 , PW 1   2 , PW 1   N ) and one or more second primary winding conductors (PW 2   1 , PW 2   z , PW 2   N ) adapted to be electrically connected in series with source portions (C 1   S , C 2   S ) and load portions (C 1   L , C 2   L ) of corresponding first and second line conductors (C 1 , C 2 ) of said electric lines (L 1 , L 2 , LN), so that common-mode electric currents flowing along said first and second primary winding conductors (PW 1   1 , PW 1   2 , PW 1   N , PW 2   1 , PW 2   2 , PW 2   N ) generate magnetic fluxes with opposite directions; 
       wherein said secondary winding means is magnetically coupleable with said first primary winding means, said secondary winding means comprising at least a first secondary winding conductor (SW 1 ) adapted to be electrically connected with said arc fault detector to provide detection signals (DS), which are indicative of AC currents flowing along said electric lines (L 1 , L 2 , LN), to said arc fault detector.